A worker at the building, who wished not to be named, said the boy was tossed from the roof.

A building surveillance video reviewed by the NYPD shows Shimron’s 20-year-old brother, identified by residents as Shawn, taking the child up one flight of stairs from the sixth floor to the top floor.

“They can’t see him going off (the building), but they can see them going up and (Shimon) falling,” the worker explained.

Shimron’s brother ran out into the street and flagged down a passing police car, but found himself in handcuffs after cops realized he may have been responsible for the tot’s death, sources said.

Charges against the older sibling, who has a history of schizophrenia, are pending.

Residents said the brother has a history of mental illness and is often seem aimlessly going up and down the building steps.